The invention concerns a method and a device for initializing convolutional interleavers at a receiver and/or a transmitter. The invention particularly applies in the frame of BRAN HIPERLAN 2 systems.
It has been proposed to include a convolutional interleaver, respectively deinterleaver in the data link control layer of a transmitter, respectively receiver, between the inner and outer error correction code encoders, respectively decoders.
The fact that a convolutional interleaver contains undetermined data at the establishment of a connection between a transmitter and a receiver results in undetermined data being sent by the receiver""s deinterleaver to the outer error code decoder. This may induce undesired behavior of the receiver.
The object of the invention is a method for transmission in a transmission system employing convolutional interleaving, characterized in that it comprises the steps of:
initiating a connection with at least one receiver;
applying an outer error encoding to dummy data;
feeding a convolutional interleaver with said error encoded dummy data at least until the memory of said interleaver contains only said error encoded dummy data; and
discarding data output by said interleaver during the previous step.
According to a particular embodiment of the invention, the method further comprises the steps of:
feeding said interleaver with useful data; and
transmitting data output by said interleaver.
According to a particular embodiment of the invention, said dummy data consists in dummy protocol data units.
Another object of the invention is a method for reception in a transmission system employing convolutional interleaving, characterized in that, it comprises the steps of:
feeding a convolutional deinterleaver with interleaved error encoded dummy data at least until the memory of said deinterleaver contains only said error encoded dummy data;
discarding data output by said deinterleaver during the previous step.
According to a particular embodiment of the invention, the method further comprises the steps of:
receiving data from a transmitter,
deinterlacing and error correcting said data.
According to a particular embodiment of the invention, the method further comprises the step of discarding deinterlaced error corrected dummy data.
The invention permits to provide a quasi error free (QEF) service quality for isochronous streams (such as audio/video streams) which by nature is not adapted to rely on an automatic repeat mechanism. It also guarantees that the receiver/decoder correctly processes all bytes transmitted during the connection. The inventive process allows to deal with the undetermined state of memories required by this convolutional coding scheme.
Another object of the invention is a transmitter in a transmission system employing convolutional interleaving, characterized in that it comprises
an error correction encoder;
a convolutional interleaver;
means for generating dummy data, feeding said dummy data to the error correction encoder and for feeding said encoded dummy data to the convolutional interleaver at least until the memory of said interleaver contains only said dummy data, and for discarding data output by said interleaver during said feeding of dummy data.
Another object of the invention is a receiver in a transmission system employing convolutional interleaving, characterized in that it comprises
a convolutional deinterleaver;
an error correction circuit;
means for generating error correction encoded interleaved dummy data and for feeding said dummy data to said deinterleaver until the memory of said deinterleaver contains only dummy data, and for discarding data output by said deinterleaver during said feeding of dummy data.